One approach is to clean up the old hatches, glue up any open joints, and
sand the insides well. Then turn the hatch upside down and fiberglass all
inside surfaces. I used one layer of 1.5 oz. matt followed by three layers
of 8 oz. cloth. Trim the glass around the edges of the hatch and varnish
inside and out. My hatches are 20 years old and have had no joint problems.
Another option is to cut away most of the top, tape a waxed piece of plywood
over the outside of the cutout, then glass the insides. When the plywood is
removed the fiberglass will form a translucent window.

"Bernard Randall" wrote in message
...
I am at the planning stage of replacing some deck hatches on a sailing
boat.
The framework is mitered, to prevent endgrain being open to the sea, but
as
these are stepped on they also need to be strong.

I see the altenatives being miters with routed slots for loose tongues, or
mitered mortice and tennons. Anyone have any experience with this type of
work?

Thanks.

BernardR